This is the O.S. Max 105HZ-R DRS Helicopter Engine. The 105HZ-R DRS is the engine that precision aerobatic and 3D heli pilots have been waiting for! In order for 90-sized machines to nail huge maneuvers and hardcore, smack down-style 3D it's all about power, and the 105HZ-R have it in abundance. Displacement has been increased by 15%, and a huge venturi rams air into the carburetor, producing massive power, while remaining small enough to fit in a .90-sized mounting pattern.
Features:

Displacement of a 1.05 in the mounting space of a .90.

More displacement means more power, and these engines boost displacement by 15%!

Huge venturi boosts output even further.

The machined, blue anodized heatsink head is light in weight, and cools the engine efficiently.